Ectopic overexpression of AtmiR398b gene in tobacco influences seed germination and seedling growth.

Xiao-Ming Feng; Yu Qiao; Ke Mao; Yu-Jin Hao

MicroRNAs play crucial roles in plant development and growth, nutrient allocation and stress responses by posttranscriptionally regulating their target genes. In the present investigation, RNA blotting studies and stem-loop RT-PCR analysis confirmed the existence, and conserved nature of miR398 in tobacco. The positive accumulation of miR398 in response to copper deficiency provided additional evidence for the involvement of miR398 in plant responses to copper homeostasis. The functional characterization of miR398 in tobacco was performed by choosing two transgenic tobacco lines containing Arabidopsis AtmiR398b gene with miR398 accumulation at different levels. The result showed that miR398 oversupply derived from AtmiR398 overexpression in tobacco down-regulated the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxide dismutase (POD) and ascorbate peroxidase (APX) possibly due to the posttranscriptional regulation of miR398 to its target genes. As a result, transgenic tobacco lines produced more O2− and H2O2, but less chlorophyll than the control. In addition, miR398 oversupply inhibited seed germination and seedling growth, especially under copper and salt stresses. The present results confirm that miR398 exists and functions in tobacco in a conserved way similar to Arabidopsis.

PLANT development; GENE expression in plants; PLANT physiology; TOBACCO; SEED viability; GERMINATION

Plant Cell, Tissue & Organ Culture, 2010, Vol 102, Issue 1, p53

0167-6857

Academic Journal

10.1007/s11240-010-9704-x